Question

Figure shows the solubility of AgNO₃ in water in units of moles of AgNO₃ per kilogram of H_2O. If 225_g of AgNO₃ is added to 100g of water at 95^oc and cooled slowly, at what temperature will the solution becomes saturated?

Short answer

Most solubility increases with increasing temperature, but some chemical decreases. Note that the changes are not always smooth because solid hydrates from over different temperature ranges.

Step-by-step solution

Step (1):-

To determine the solubility of AgNO₃ at a certain concentration and temperature we can use figure which is a solubility concentration curve given in mol/kg at a given temperature. First calculate the moles of AgNO₃ as follows:

$255gAgN{O}_{3}X\frac{1mplAgN{O}_3}{169.87gAgN{O}_3}=1.5molAgN{O}_3$

Now calculate the volume of water in which AgNO₃ is dissolved:

$100g{H}_{2}0X\frac{1kg{H}_{2}O}{1000g{H}_{2}O}=0.1kg{H}_{2}O$

Finally calculate the concentration, molarity (M) of the AgNO₃ solution as follows:

$\frac{1.5molAgN{O}_3}{0.1Kg{H}_{2}O}=15molk{g}^{-1}AgN{O}_3$

Step (2):-

The following graph represents, the solution cooled down , and it becomes saturated. Thus, the line interest

at 15mol/kg and the temperature is 30^oc.

There, the solution of 15mol/kgAgNO₃ becomes saturated at $\boxed{{30}^{o}c}$.